1. Field of the Invention
The present invention relates to a computer system, and more particularly, to a single chip computer system having integrated NPEG and graphical processors.
2. Description of the Related Art
Microprocessors have been used for many years as a primary component of computer systems. Conventionally, a microprocessor is a single chip device that includes a central-processing unit (CPU), registers, I/O and interrupt managers, etc. High performance microprocessors also typically include a built-in coprocessor or a functional unit dedicated to performing floating-point computations.
Recently, graphics and video has become popularized and desirable to many computer users. Specialized graphics support is needed to obtain high quality graphics. Likewise, specialized video support is needed to display moving pictures read from compact-disks or downloaded from a remote server. The existing video compression standard that is often supported is MPEG.
In conventional designs of computer systems that are built to support normal processing as well as graphics and MPEG processing, the hardware or circuitry for all the needed processing is provided by two or more separate integrated circuits. Recently, LSI Logic Corporation of Milpitas, Calif. has produced an integrated circuit chip (Sony-PSx) for Sony Corporation that combined a JPEG like processor and a geometry transformation processor onto a microprocessor chip. However, additional supporting chips were still be required to perform MPEG, display control, and boot-up operations. Also, the interfacing of these supporting chips to the microprocessor chip was very costly in terms of the number of pins required on the microprocessor chip itself. For example, to interface the microprocessor to a MPEG coprocessor would likely require over one-hundred (100) connections (pins) between the microprocessor and the MPEG coprocessor. Having to provide such microprocessor to coprocessor interface is a substantial burden on microprocessor designers and impairs the ability of the microprocessor to support other operations.
Moreover, due to the complexity of the microprocessor and the various coprocessors needed, previously it has been physically impossible or too difficult to combine all the needed functionality into a single integrated circuit chip. As a result, since each of the processors requires significant memory capacity and bandwidth, dedicated memory had to be separately provided in the various chips. The dedicated memories were normally built to handle peak needs of the processor. For example, the memory needs of a microprocessor varies with application size, the memory needs of a graphics processor varies with the size and complexity of the images being rendered, and the memory needs of a MPEG processor varies with picture size. As a result, in conventionalmultimedia computer system designs memory usage was inefficiently utilized. Inefficient usage of memory is problematic because memory is a major cost component of producing such integrated circuits.
Existing microprocessor designs also offer no protection against unauthorized access to program code or data. With multi-chip implementations, an authorized user typically has access to the pins of the chips that interface to the microprocessor and can intercept program code and data therefrom.
Thus, there is a need for a single chip computer system that supports not only normal processing operations but also provides specialized support for graphical and video processing operations. There is also a need for a computer system that provides improved security for program code and data.